Frame components, such as, jambs and mullions, for exterior door systems are exposed to environmental elements and extremes such as moisture, temperature, and sunlight, which can attack and break down the frame material. Protective coatings such as exterior grade paints are typically used not only to improve appearance but also to protect the underlying material, which is traditionally and typically wood. These frame components are also prone to moisture wicking up from their bottom ends. This type of moisture can lead to decay over time, which compromises the appearance and structural integrity of the frame. Alternates to a traditional wood frame include aluminum cladded wood frames, which can be expensive, vinyl cladded wood frames, which are not very resistant to impact damage, or all-plastic extruded frames, which are not very rigid and are also susceptible to deformation under heat.
While all-plastic frames are typically more resistant to environmental degradation and may decrease maintenance needs, conventional all-plastic frames often include reduced structural strength. Other frames have included stiffening components of laminated wood or metallic type extrusions in attempts to address structural integrity limitations, however, such stiffening components create other challenges, by way of example, interfering with hardware fasteners used to anchor frames and frame components.
Thus, there remains a need for a new and improved door assembly and frame members that are decay resistant while, at the same time, have the appearance and strength of a traditional wood frame door assembly.